Multimedia Broadcast and Multicast Service

This chapter provides information on Multimedia Broadcast and Multicast Service (MBMS) functionality on GGSN. The product Administration Guides provide examples and procedures for configuration of basic services on the system. It is recommended that you select the configuration example that best meets your service model, and configure the required elements for that model, as described in the respective product Administration Guide, before using the procedures in this chapter.

IMPORTANT:

The features described in this chapter are only available if you have purchased and installed MBMS feature support license on your chassis.

This chapter discusses following topics for MBMS support:
  • Introduction
  • Supported Standards
  • Supported Networks and Platforms
  • Services and Application in MBMS
  • How MBMS Works
  • MBMS Configuration
  • Save the Configuration
  • Managing Your Configuration
  • Gathering MBMS Statistics

Introduction

MBMS is an IP datacast type of service in GSM and UMTS cellular network. It eliminates unnecessary replication of data on UMTS wireless networks by transmitting a single stream of data to multiple users. By delivering a single, unidirectional data stream to many subscribers, MBMS makes more efficient use of wireless network resources than traditional point to point connections.

MBMS is a solution for transferring light video and audio clips with a suitable method for mass communications.

MBMS functionality on the system is provided by an existing GGSN service and is enabled by a valid services license.

The main features supported by the Multimedia Broadcast & Multicast Services are:
  • Individual user network control functions and provide forward MBMS user data to SGSN

    IMPORTANT:

    The Cisco chassis supports 225 downlink SGSNs per MBMS Bearer Service through NPU assisted data flow processing. NPU assisted data processing is available on the systems with release 8.1 or later only.

  • Support for intra-GGSN and inter-GGSN mobility procedures
  • Generate charging data per multicast service for each user for both prepaid and post paid subscribers.
  • Multicast proxy-host functionality
  • Support for MBMS-specific Gmb messages
  • Authentication of MBMS flow-ids using a MBMS controller
  • Establishment and tear-down of MBMS bearer paths using the multicast framework
  • Support for framing HDLC-like and segment based framing
  • Accounting for the MBMS flows to charge the originator of the content
This service provides two mode of operations:
  • MBMS Broadcast Mode
  • MBMS Multicast Mode

A broadcast mode is a unidirectional point-to-multipoint service in which data is transmitted from a single source to multiple terminals (UE/MS) in the associated broadcast service area/cell area. The transmitted data can be text to light multimedia services (Audio, Video etc). On the other hand multicast mode is a unidirectional point-to-multipoint service in which data is transmitted from a single source to a pre-defined multicast group of users that are subscribed to the specific multicast service and have joined the multicast group in the associated multicast service area.

The following figure shows the reference architecture of MBMS service in UMTS network.


Figure 1. MBMS Reference Architecture in UMTS network
The GGSN provides the following functionality to perform MBMS services:
  • serves as an entry point for IP multicast traffic as MBMS data. It provides establishment of bearer plan and tear-down of the established bearer plan upon notification from the BM-SC.
  • provides functionality to receive MBMS specific IP multicast traffic and to route this data to the proper GTP tunnels set-up as part of the MBMS bearer service.
  • provides features, that are not exclusive to MBMS, for the MBMS bearer service, like charging data collection, flow-based charging, optional message screening etc.

MBMS is able to use NPU assisted MBMS data flow processing on chassis so that system can relieve the Session Manager to provide better performance and processing. Currently with NPU assisted data processing, the Cisco chassis can support 225 SGSNs per MBMS Bearer Service for downlink of MBMS data.

Supported Standards

Support for the following standards and requests for comments (Rafts) have been added with the MBMS functionality:

  • 3GPP TS 22.146: Multimedia Broadcast/Multicast Service; Stage 1 (Release 6)
  • 3GPP TS 22.246: MBMS user services; Stage 1 (Release 6)
  • 3GPP TS 23.246: MBMS; Architecture and functional description (Release 6)
  • 3GPP TS 26.346: MBMS; Protocols and codecs (Release 6)
  • 3GPP TS 33.246: Security of Multimedia Broadcast/Multicast Service
  • 3GPP TS 32.251: Telecommunication management; Charging management; Packet Switched (PS) domain charging
  • 3GPP TS 32.273: Telecommunication management; Charging management; Multimedia Broadcast and Multicast Service (MBMS) charging
  • RFC 3588, Diameter Base Protocol

Supported Networks and Platforms

This feature supports all Cisco chassis running StarOS Release 8.0 or later with GGSN service for the core network services.

License Information

Note:

Use of MBMS feature requires that a valid license key be installed. Contact your local Sales or Support representative for information on how to obtain a license

Services and Application in MBMS

MBMS service can be used as an enabler for various data streaming services. Compared to traditional broadcast services like cell broadcast, MBMS provides multimedia capabilities with relatively high data rates and considerably greater multimedia capabilities.

Some of the applications for MBMS are:
  • News clips
  • Audio streams
  • Combined audio and picture/video clips
  • Video distribution services, either via streaming, carousel, or download methods
  • Localized services like tourist information, weather alerts etc.
  • Content distribution
  • Game delivery

The charging of the MBMS bearer service can be done based on events, content, or flows.

MBMS provides the authentication, key distribution, and data protection for the multicast service users.

MBMS References and Entities

Following are the major components and entities required for MBMS service.

Gmb Reference

The Gmb reference point handles the broadcast multicast service center (BM-SC) related signaling, which includes the user specific and bearer service messages.

MBMS bearer service specific Gmb signaling includes:
  • MBMS bearer context establishment by GGSN and registering of GGSN at BM-SC.
  • Release of MBMS bearer context at GGSN and de-registration of GGSN from the BM-SC.
  • Session start/stop indication from BM-SC to GGSN including session attributes like QoS or MBMS service area.
User specific Gmb signaling includes:
  • BM-SC authorization of user specific MBMS multicast service activation at the GGSN.
  • Reporting of successful user specific MBMS multicast service activation by GGSN to BM-SC to synchronize the BM-SC UE MBMS context and charging with the MBMS UE contexts in GGSN.
  • Reporting of release or deactivation of user specific MBMS multicast service activation by GGSN to BM-SC to synchronize the BM-SC UE MBMS context and charging with the MBMS UE contexts in GGSN.
  • BM-SC initiated deactivation of user specific MBMS bearer service when the MBMS user service is terminated.

MBMS UE Context

A MBMS UE context is defined per UE. Session Manager assign a separate context structure for a MBMS UE Context.

Session Manager maintains the following information as part of MBMS UE Context:
  • IP multicast address: IP multicast address identifying an MBMS bearer that the UE has joined.
  • APN: Access Point Name on which this IP multicast address is defined.
  • SGSN address: The IP address of SGSN
  • IMSI: IMSI identifying the user.
  • TEID for Control Plane: The Tunnel Endpoint Identifier for the control plane between SGSN and GGSN.
  • MBMS NSAPI: Network layer Service Access Point Identifier which identifies an MBMS UE Context.

    IMPORTANT:

    For capacity and resource purpose one MBMS UE context is equal to one PDP context.

MBMS Bearer Context

The MBMS bearer context is created in the SGSN and GGSN for each provisioned MBMS service. This is created when the first MS requests for this service or when a downstream node requests it. Once created, an MBMS context can be in two states:

  • Active - is the state in which network resources are required for the transfer of MBMS data.
  • Standby - is the state in which no network resources are required.

The MBMS Bearer Context contains all information describing a particular MBMS bearer service and is created in each node involved in the delivery of the MBMS data.

Broadcast Multicast Service Center (BM-SC)

The BM-SC includes functions for MBMS user service provisioning and delivery. It serves as an entry point for content provider MBMS transmissions, used to authorize and initiate MBMS Bearer Services within the PLMN. It can also be used to schedule and deliver MBMS transmissions.

The BM-SC consists of five sub-functions:
  • Membership function
  • Session and Transmission function
  • Proxy and Transport function
  • Service Announcement function
  • Security function.

BM-SC is a functional entity and must exist for each MBMS User Service.

How MBMS Works

The Multimedia Broadcast Multicast System provides two types of service provisioning; broadcast and multicast modes. This section describes the procedure of these modes.

MBMS Broadcast Mode

The broadcast mode provides unidirectional point-to-multipoint type transmission of multimedia data from a single source to all users that found in a defined broadcast service area. This mode uses radio resources efficiently, since the data is transmitted over a common channel.

MBMS data transmission adapts to the suitable RAN capabilities, depending on the availability of radio resources too. If needed, the bit rate of MBMS data may be varied in order to optimized radio resources.

The following figure shows the basic outline of broadcast mode procedure of an MBMS service in order to broadcast MBMS data within the defined broadcast service area via a packet switched core network.


Figure 2. Basic Procedure of MBMS Broadcast Mode

The broadcast service may include one or more successive broadcast sessions. The user can control the enabling or disabling of the MBMS broadcast mode service.

MBMS Broadcast Mode Procedure

The MBMS performs following steps for broadcast mode user service:

  1. Service Announcement: Through the service announcement mechanisms, like SMS, WAP, users informed about the available MBMS services.
  2. Session Start: This is the phase where BM-SC has data to send and this triggers establishment of network resources for data transfer irrespective of whether a given user has activated the service or not.
  3. MBMS Notification: Notifies the MS of a impending MBMS data transfer.
  4. Data Transfer: It is the phase when MBMS data are transferred to the UEs.
  5. Session Stop: In this phase, the BM-SC determines that it has no more data to send for a time period and so the network resources can be released.

MBMS Multicast Mode

The multicast mode provides unidirectional point-to-multipoint type transmission of multimedia data from a single content source to a group of subscribers that subscribed to specific multicast service separately. The basic difference between broadcast and multicast modes is that the user does not need to subscribe in each broadcast service separately, whereas in multicast mode the services cab be order separately. The subscription and group joining for the multicast mode service can be done by the operator, user, or a separate service provider.

Like broadcast mode the multicast mode allows the unidirectional point-to-multipoint transmission of multimedia data within the multicast service area. The multicast mode uses radio resources in efficient way by using common radio channel as in broadcast mode. Data is transmitted over the multicast service area as defined by the network operator.

The multicast mode provides the flexibility for the network to selectively transmit to those cells within the multicast service area that contains members of a multicast group.

The following figure shows the basic outline of multicast mode procedure of an MBMS service in order to multicast MBMS data within the defined multicast service area via a packet switched core network.


Figure 3. Basic Procedure of MBMS Multicast Mode

A multicast service might consist of a single on-going session or may include several simultaneous multicast sessions over and extended period of time.

Some example of multicast mode service are:
  • transmission of sports video clips to subscribers on charging basis
  • transmission of news, movie, song, and audio clips to subscribed users on charging basis

MBMS Multicast Mode Procedure

The MBMS performs following steps for multicast mode user service:

  1. Subscription: Establishes the relationship between the user and the service provider, which allows the user to receive the related MBMS multicast service.
  2. Service Announcement: Through the service announcement mechanisms like, SMS, WAP, users shall be informed about the available MBMS services.
  3. Joining: This is the process by which a subscriber joins a multicast group, i.e. the user indicates to the network that he/she wants to receive Multicast mode data of a specific MBMS bearer service.
  4. Session Start: This is the phase where BM-SC is ready to send data and this triggers establishment of network resources for data transfer irrespective of whether a given user has activated the service or not.
  5. MBMS Notification: Notifies the MS of a impending MBMS data transfer.
  6. Data Transfer: It is the phase when MBMS data are transferred to the UEs.
  7. Session Stop: In this phase, the BM-SC determines that it has no more data to send for a time period and so the network resources can be released.
  8. Leaving: In this phase, the user leaves a MBMS group through an Internet Group Management Protocol (IGMP) Leave message.

MBMS Configuration

This section provides a high-level series of steps and the associated configuration examples for configuring the system with MBMS user service in GGSN services.

IMPORTANT:

These instructions assume that you have already configured the GGSN/SGSN system level configuration as described in network function Administration Guide.

To configure the system to perform Multimedia Broadcast and Multicast service:

  1. Configure the BM-SC profile in a context by applying the example configurations presented in the BMSC Profile Configuration section.
  2. Configure the MBMS charging parameters in GTPP Server Group Configuration mode by applying the example configurations presented in the MBMS GTPP Configuration section.
  3. Configure the MBMS accounting, supported contexts, timeout parameters, and BMSC profile association with APN in APN configuration mode by applying the example configurations presented in the MBMS APN Configuration section.
  4. Enable the MBMS user service provisioning mode in GGSN and configure the number of MBMS UE and MBMS bearer context in GGSN configuration mode by applying the example configurations presented in the MBMS Provisioning section.
  5. Save the changes to system configuration by applying the example configuration found in Verifying and Saving Your Configuration chapter.
  6. Verify configuration of MBMS service related parameters by applying the commands provided in the Managing Your Configuration section of this chapter.

BMSC Profile Configuration

This section provides the configuration example to configure the BM-SC profile in a context:

configure

   context <vpn_context_name> [ -noconfirm ]

      bmsc-profile name <profile_name> [ -noconfirm ]

         default gmb diameter dictionary

         gmb diameter endpoint <endpoint_name>

         gmb diameter peer-select peer < peer_name> [ realm <realm_name> ] [ secondary-peer <sec_peer_name> [ realm <sec_realm_name> ]]

         default gmb user-data
mode-preference

         end

MBMS GTPP Configuration

This section provides the configuration example to configure the GTPP server parameters in GTPP group configuration mode for MBMS charging:

configure

   context <vpn_context_name> [ -noconfirm ]

      gtpp group default

         gtpp mbms buckets <cc_bucket>

         gtpp mbms interval <duration_sec>

         gtpp mbms tariff time1 <mins> <hours> [ time2 <mins> <hours> ]

         gtpp mbms volume <download_bytes>

         end

MBMS APN Configuration

This section provides the configuration example to enable the BM-SC profile for an APN and to configure the MBMS accounting, supported contexts, and timeout parameters in APN configuration mode:

configure

   context <vpn_context_name>

      apn <apn_name> [ -noconfirm ]

         mbms bmsc-profile
name <profile_name>

         default max-contexts

         accounting mode gtpp

         default mbms bearer
timeout { absolute | idle }

         default mbms ue timeout absolute

         end

MBMS Provisioning

This section provides the configuration example for provisioning of MBMS service mode for a GGSN service and associating the MBMS policy for multcast broadcast within the GGSN service in GGSN service configuration mode:

configure

   context <vpn_context_name>

      ggsn-service <ggsn_service_name>

         mbms policy multicast broadcast

         end

Save the Configuration

To save changes made to the system configuration for this service, refer Verifying and Saving Your Configuration chapter.

Managing Your Configuration

This section explains how to display and review the configurations after saving them in a .cfg file as described in Saving Your Configuration chapter of this guide and also to retrieve errors and warnings within an active configuration for a service.

IMPORTANT:

All commands listed here are under Exec mode. Not all commands are available on all platforms.

Output descriptions for most of the commands are located in Command Line Interface Reference.
To do this: Enter this command:

View Administrative Information

Display Current Administrative User Access
View a list of all administrative users currently logged on to the system

show administrators

View the context in which the administrative user is working, the IP address from which the administrative user is accessing the CLI, and a system generated ID number

show administrators session id

View information pertaining to local-user administrative accounts configured for the system

show local-user verbose

View statistics for local-user administrative accounts

show local-user statistics verbose

View information pertaining to your CLI session

show cli

Determining the System’s Uptime
View the system’s uptime (time since last reboot)

show system uptime

View the Status of Configured NTP Servers
View the status of the configured NTP servers

show ntp status

View the Statistics of Broadcast Multicast service
View the full information of all broadcast-multicast service session

show multicast-sessions full all

View the status of all broadcast multicast-service session

show session in-progress

View all session for broadcast-multicast service

show multicast-sessions all

View Subscribers Currently Accessing the System
View a listing of subscribers currently accessing the system

show subscribers all

View information for a specific subscriber

show subscribers full username <user_name>

View the MBMS Related Information

Display Configured MBMS service
View the configuration of a context

show configuration context <vpn_ctxt_name>

View configuration errors for GGSN service

show configuration errors section ggsn-service [ verbose ] [ | {grep <grep_options> | more } ]

Display BM-SC server Information

show bmsc servers



Gathering MBMS Statistics

The following table lists the commands that can be used to gather the statistics for MBMS.

IMPORTANT:

All commands listed here are under Exec mode. For more information on these commands, refer Executive Mode Commands chapter in Command Line Interface Reference.


Table 1. Gathering Statistics
Statistics Wanted Action to Perform Information to Look For

Gmb interface statistics for APN and BM-SC profile
At the Exec Mode prompt, enter the following command:
show gmb statistics [ apn <apn_name> | bmsc-profile <bmsc_profile_name> ] [ verbose ]

The output of this command displays the statistics about the Gmb interface session for MBMS on an APN.

Detailed MBMS bearer service statistics
At the Exec Mode prompt, enter the following command:
show mbms bearer-service [ mcast-address <mcast_address> ]  [ apn <apn_name> ]  [ bmsc-profile <bmsc_profile_name> ]  [ service-type { multicast | broadcast } ] [ summary | full ] [ all ]

The output of this command displays the MBMS bearer service statistics.

Detailed statistics of MBMS multicast sessions
At the Exec Mode prompt, enter the following command:
show multicast-sessions

The output of this command displays the detailed statistics of MBMS multicast session running on system.